Physical activity may help to protect the brain in those at risk of developing Alzheimer’s disease, a new study showed. The findings suggest that exercise is good for the brain and may help to ward off Alzheimer’s and other forms of dementia with advancing age, particularly in those with a family history of the disease.
For the study, researchers scanned the brains of nearly 100 healthy seniors who were free of dementia. They ranged in age from 65 to 89. The scientists focused on the hippocampus, a seahorse-shaped structure critical for memory and thinking and one of the first areas to be affected by Alzheimer’s disease.
The study participants were also asked whether they had a family history of Alzheimer’s disease, and they were tested for a gene called APOE-E4, which raises Alzheimer’s risk. The APOE gene is involved in fat and cholesterol transport in the body. Those who carry the E4 version of the gene are two to 10 times more likely to develop Alzheimer’s than those who carry other versions of the APOE gene, though not everyone with the gene will ultimately develop dementia.
In addition, study volunteers completed surveys about how often they exercised in a typical week. Those who got very little exercise or who had two or fewer days of light activities like slow walking or doing household chores were considered to be physically inactive. Those who engaged in more rigorous activities three or more days a week were considered to be physically active. Vigorous activities included brisk walking, jogging or swimming for 15 to 30 minutes or longer, doing moderately difficult chores for at least 45 minutes, or playing sports such as handball or tennis for an hour or longer.
After 18 months, the researchers scanned the brains of the participants for a second time. In those volunteers who were physically inactive and who carried the APOE-E4 gene and were thus at high risk of developing Alzheimer’s disease, the hippocampus shrunk in volume by 3 percent. A shrinking hippocampus is a sign that the brain may be succumbing to the brain deterioration of Alzheimer’s.
There was no shrinkage of the hippocampus, however, in those APOE-E4 carriers who were physically active. Nor was their brain shrinkage in those who didn’t carry the gene, regardless of how often they exercised. The findings were published in the journal Frontiers in Aging Neuroscience.
The results suggest that physical activity may be particularly beneficial for those with a family history of Alzheimer’s disease. And they bolster the findings of earlier research. One study from 2013, for example, found that among APOE-E4 carriers, those who were physically active tended to have less buildup in the brain of beta-amyloid, a toxic protein that is a hallmark of Alzheimer’s disease. Another found that physically active seniors tended to score higher on memory tests than their sedentary peers.
Scientists aren’t sure how exercise may counter the deleterious effects of APOE-E4 on the brain. But animal studies suggest that exercise may reduce inflammation, promote the growth of new brain cells, promote healthy blood flow and prevent buildup of beta-amyloid, all of which may help to preserve brain performance.
More research needs to be done to better understand the links between genetics, exercise and brain health. But in the meantime, the researchers suggest, it would be wise for anyone at risk of Alzheimer’s to maintain a regular exercise routine.
Source: J. Carson Smith, Kristy A. Nielson, John L. Woodard, et al: “Physical Activity Reduces Hippocampal Atrophy in Elders at Genetic Risk for Alzheimer’s Disease.” Frontiers in Aging Neuroscience, Vol. 6: 61, published online April 23, 2014